Is there a limit in Excel 2003 to the number of digits a number can contain?

When I enter the number 4912150001548892, Excel is changing it to 4912150001548890. It does not seem to matter the format of the cell, General or Number. Other numbers of the same length seem to enter with no issues, 4912150001748877.

Numbers have a limited precision of about 16 digits (sometimes 15, sometimes 16 depending on the number), which is usually more than enough for mathematical calculation. If you need to store this number exactly and don't plan to do math on it, type a single quote before it. It will be displayed without the single quote and treated as a text.